Tools for de-hiding carcasses are well-known in the industry, and various improvements to de-hiding tools are disclosed in U.S. Pat. Nos. 4,368,560 to Wetzel et al., 5,122,092 to Abdul, and 4,901,400 to Karubian. Generally speaking, these tools have oppositely reciprocating cutting blades which are usually disk-shaped with serrated outer edges. The blades are driven by an air motor at very high speeds, in one embodiment approximately 6,500 rpm.
It is important to minimize the amount of waste material that tends to collect between the blades during use in order to avoid the tool becoming unsanitary and inefficient in its cutting. To confront this problem, the blades in prior art de-hiders are put under face-to-face pressure by various spring mechanisms that press one blade face against the other. As these blades reciprocate in opposite directions each to the other, friction and wear are developed by the spring element. Some prior art de-hiders have used a wave spring that becomes worn and fails due to fatigue under the high speed operating conditions that exist. Replacement of the wave spring is expensive and time consuming, and with the devices of the prior art it must occur quite frequently. The present invention provides an improvement to the techniques for maintaining face-to-face pressure contact on the blades during use.
There is also a need to develop a de-hiding tool having reduced weight and which minimizes noise and vibration during use. One prior art de-hiding tool, such as that disclosed in my '400 patent, uses an integral handle and blade-supporting frame made of aluminum to reduce weight. This design includes three spaced apart holes on the frame for receiving fastening devices for attaching the blades to the drive arms and to a cover secured to the outside of the tool housing. During use, the tool is constantly being twisted manually, which applies substantial lateral forces that flex the cutting blades. As a result, the frame of the tool where the holes are located was prone to cracking or breaking.
A subsequent design that was intended to overcome this problem replaced the aluminum frame with a handle and blade cover made of steel, using a center insert-type bearing as a spacer for mounting the cutting blades inside the housing cover. This tool mounts the blades to a cantilevered supporting shaft contained inside the blade covers. Because of the mounting arrangement of the blade supporting shaft, the shaft has been prone to cracking or breaking under the lateral forces applied to the blades during use.
There is also a need to improve cutting efficiency and to reduce the time lost when the tool is disassembled for sharpening the blades. As the blades become dull during use, the tool must be disassembled and the blades reground, typically by a hollow grinding process. Each time the blades are reground they become thinner. Eventually this creates a problem of the confronting blade faces being spaced so far apart that their cutting efficiency is reduced, in a manner similar to scissor blades that are spaced too far apart. The past systems for maintaining pressure on the confronting faces of the blades are not only subject to wear and breakage problems, but they do not adequately solve the problem of compensating for the thinner blades that result from the regrinding process.
Thus, there is a need to improve the wear life of the blade support system, to maintain cutting efficiency over a longer period of time, to reduce the time lost in reconditioning the cutting blades, and to reduce the adverse effects of vibration and the weight of the tool during use. There is also a need for a blade adjustment system that can be efficiently used to readily make adjustments to compensate for blade wear.